A leukemoid reaction is an increase in the white blood cell count, which can mimic leukemia. The reaction is actually due to an infection or another disease and is not a sign of cancer.
Blood counts often return to normal when the underlying condition is treated.
Rice L, Jung M. Neutrophilic leukocytosis, neutropenia, monocytosis, and monocytopenia. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 48.
Reviewed By: Preeti Sudheendra, MD, oncologist at the MD Anderson Cancer Center at Cooper, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.